The present invention is concerned with that aspect of the electrochemical field related to solid state electrochemical cells employing lithium metal (or alloy) anodes. In a solid state electrochemical cell the utility of the cell with a given cathode and anode is greatly influenced by the characteristics of the electrolyte. A suitable electrolyte must be an electronic insulator and an electrolytic conductor. The greater the electrolytic conductivity of the electrolyte, all other factors being equal, the greater is the allowable current drain from the cell and the less is the internal resistance of the cell. By the present invention there are provided novel solid state electrolytes having high electrolytic conductivity as well as high electronic resistivity.